I'm probably completely wrong on this but could these photos be of the same woman?
Author on the left is Caro Peacock, whose first book, Death at Dawn, has just come out. Author on the right is Gillian Linscott, whose last book came out in 2003. (A more recent but lower resolution photo is on the reviewingtheevidence site.)
From the author information on Death at Dawn: "Caro rides horses, climbs trampolines and spends some time every year studying wild flowers in the Alps."
From Tangled Web - Gillian Linscott has "passions for horse-riding and hill-walking."
Death at Dawn which is the first in the Liberty Lane series is set in 1837 and Gillian Linscott's Nell Bray series is set in the early 1900s.
Not much to go on, just a feeling of familiarity when I looked at the author photo on the jacket. Either way, Death at Dawn looks well worth checking out. The opening line is: "Would you be kind enough to tell me where they keep people's bodies".